Beware hidden charges

I booked a car from Thrifty for Dublin for 17 days. I am a regular car hirer for holidays and EU short breaks and the cost of CDW and Theft Insurance has always formed part of the basic price. On arrival at the desk to collect the car, I was advised that I had to pay extra for these insurances and a full tank of petrol - this more than doubled the rental cost. I had family waiting outside of the main airport hire area and all I could do was to complain but this was to no avail - indeed I was told that I should have realised from the price that this would be the case (not true as I had obtained similar quotes from others months earlier). I had to pay and was sickened by the experience of not being advised prior to this that it would be added on. Apparently the site I used was a US site, hence the difference (how was I to know that?). I have since price compared via other car hire intermediary sites taking the Thrifty offer as the one and found the CDW/Theft insurance offered to be INCLUSIVE!
I consider this practice to be grossly misleading. What you think you are going to pay is NOT what you will pay - beware! I am seeking to take this further.