Haywards Couture Dry Cleaners & Tailors Attempted to Charge GBP 50 for sewing 3 fasteners and the fasteners even came from me! Internet

I chanced upon Haywards Couture Dry Cleaners/Tailors on 25B Lowndes Street, London SW1X 9JF.  Initially a lady (who I later on found out was the wife of Arnold Berman, the owner) very kindly assisted me in my query to put 3 fasteners on a coat.  She said it could be done immediately and quoted me GBP 20 for the job (I was provided the fasteners). She said to come at any time.  I told her I'd return on Friday afternoon and that I'd wait for the coat at a nearby cafe. She said no problem. 

Return on Friday and gave the quote to ARnold Berman, her husband.  He told me they were "busy" and I told them what his wife said. He took the coat and asked me to come back in 20 minutes.  20 minutes later I came back expecting to pay GBP 20 as his wife had indicated (which is already double the price of tailoring in other posh parts of the city).  

The man insisted on charging me GBP 50 to fasten 3 fasteners on my coat (and the fasteners were supplied by me). I was shocked. He insisted it was a "rush job" but never gave me the quote in advance of taking the job. He was very rude and challenged me to complain on what is clearly price gouging of the consumer.  

DO not let businesses like this get away with predatory behaviour.