Poor service

I took my VW Polo to Thompsons Motor's (Louis Trichard) for a timing setting, because the car was jerkking and misfiring upon arrival I was again asked as to why the car was jerkking and misfiring and I again explained that the car was from another mechanic who had put in a new top gasket and pistons but could not do the timing perfectly, so they said they will diagnose it first for R403 of which we agreed on, they took the car in. I was called and told that the timing setting would cost R8000 of which I declined because I felt like the price was way too much so I went there for a breakdown of the amount and spoke to the workshop manager Mr Frank Adams who was of no assistance in explaining how they arrived on such a figure.They forced me to pay R2400 on collection of the vehicle without any job done or daignosis report, I feel it was a rip off of my hard earned cash and would not recommend anybody to send in their vehicles for repairs at that branch, ill treatment and Poor service.