Opel moka service

I took my opel moka in for a service on Thursday the second of November witch Adula quoted me for a couple of days earlier a total of R4850 I was very happy with that price as it was a couple of hundred rand cheaper than my previous service I paid for at Steve's auto clinic....so on the 2nd of November I brought in my car for the service and saw them advertise a polish for 550 only to be told because I drive a SUV that price would be R690 and I understand that so I left my car there thinking that my service and polish would come to round about R5540 right ¿ only to be called later that day saying my total is R6800 ...when I asked Abdul why the sudden fluctuation in price he told me he would look in to it ....so I eventually ended up paying R6600 because of "spark plugs " as he told me ......I also see som plastic trim as magically dissappeard from my car ....is this the type of service everyone gets at Williams hunt port Elizabeth?????