Thanks for the advice guys. I think i will send him a letter cancelling the service. 
Until I read this bit I was going to write that if you really still need this customer, ditch the inside cleaning of the porch and keep it at £15 (let him know that you are stopping the inside of the porch too). However, if he really was rude about it, I just wouldn't bother. I try to respect my custies and expect a bit of respect back. No need for either party to be a doormat.
Just one question though: Did you give notice of the price increase - e.g. "from my next visit I will be increasing the price to £x". If you gave no notice and just did the clean and ask for more money then I think he's every right to feel a bit miffed - but only for that one clean.