About to cancel my direct debit to Vision Express!

I have just received a letter to say that my direct debit is to increase to £20.50 per month which is the 'straw that broke the camels back'
I had a text in November about an aftercare contact lens appointment that I should have attended in September and as I hadn't attended (knew nothing about it)they would not send me my 3 month supply of lenses (due to me and paid by me)in the first week of December.I explained that I was unable to attend an aftercare appointment in December but I would do in January when I was free and asked them to send me one pair of lenses to be going on with.No was the answer,as I hadn't had an aftercare check up,'its illegal for us to send out a pair as you haven't had an aftercare appointment' stated by an extremely belligerent assistant!So its ok and safe for me to wear monthly lenses for 2 months?!
Prices now increased,no customer service, phone charges to ring H.O,can get lenses £160 cheaper per year on internet, 13 years and £3k spent with them...so they have finally pushed me to go elsewhere!! Losers!!