Poorly handled, no responsibility for mistakes, disappointed

Having purchased two cars from Arnold Clark in the past I felt confident in going to them for another purchase. My mum and I visited the branch to view an estate vehicle on a weekday evening after work, had been encouraged by the sales colleague to put a reservation deposit of £100 on the vehicle until we could return at the end of the week for a test drive as he repeatedly said the vehicle would be gone before we could return. Having left a deposit for reservation a family health emergency the night before we were due to return to the branch meant we had to cancel. I called first thing the day we were due to return to advise we would be unable to visit, and due to the circumstances would like the reservation removed and deposit refunded. I was unable to speak to the sales assistant we'd dealt with due to a meeting, left a message with the receptionist who sounded confident it would be handled. I received a call back from the sales assistant half an hour later. When I told him the circumstances and that I would like the reservation removed he kept asking why and couldn't we rearrange. My grandad had been taken into hospital overnight with a stroke, I had no idea what the outcome would be and just needed to know the reservation was removed so I could get on. I can only explain his attitude as huffy. He sighed down the phone when he realised I wasn't going to change my mind and mumbled "alright give me a minute" then hung up. I assumed he would phone back, however three hours later he hadn't. I left a further message with the receptionist who advised the sales colleague was with a customer, she remembered my first call from the morning and asked if he had dealt with my call yet. I told her he had called back initially, but had not called again to arrange refund of the deposit or confirm the reservation had been removed. Two hours later I had not been called back. I had to go to work and so my mum, who was angry at the lack of customer care during a stressful time for us, called the branch. She managed to finally speak to the sales colleague who apparently mumbled his way through an explanation that he had been waiting all day for his manager to authorise removing the reservation. Why was this not communicated then? I feel he ignored our calls because he was annoyed we hadn't bought the car. I should have known from the attitude during the visit to first view the vehicle. He asked after a five minute walkaround of the vehicle if we were going to buy it. A further 'mistake' occurred a day or so later when we received a call from the sales colleague where he told us he had put through the car as a sale in my name and probably a V5 was getting sent out, oh and could we return it ASAP. My mum who had taken the call was by this point really frustrated, he gave no explanation or apology and when she said we'd post the V5 back if we received it he said it would really be better if we could hand it in to the dealership. We live well over an hour away from them so no! I didn't receive a V5 so assumed they had managed to rectify their c*ck-up. However I got a letter in the post last week from the DVLA warning that I was listed as keeper of the car, another application for ownership had been lodged, and if I didn't inform them of correct ownership soon I could be charged with an offence. I am extremely angry I have had to deal with this during a stressful time. The attitude of the sales colleague, who I haven't named because I feel that singling out a new salesman in the branch is unnecessary, and the general incompetence and unprofessional way of handling customers is shocking. I am disappointed and will be avoiding Arnold Clark branches in the future. Sighthill branch need to take a look at the way they operate.