Very bad and not trustworthy service from the Kempton Park branch

Very bad and not trustworthy service . I took my car for a major service , which I specifically stated they must change plugs. After a month, the vehicle started losing power and the oil was black . I went back, and they told me they didn't change the plugs because my plugs are platinum and they don't know why the oil is black. So, they charged me for a major service to do a minor service with cheap oil , and if it is platinum, they don't change plugs.