Useless service at GM barloworld centurion

I went to took in my vehicle in to change my airflow sensor at monday 02-02-2015,as they were fully booked i had to take back my bakkie on wednesday 4-2-2015 at 7h00am. I gave in my service book as well as an extra policy that they can claim the parts needed to fix my vehicle. I also said to riaan at the helpdesk on service side that if that policy dont pay the full amount of parts and labour that i have an other policy that will pay the rest out. I arranged that if the part is not there or the policy did not pay yet that i can take my vehicle back to use while we wait for the part or the policy to pay out. Since wednesday i had took my car back to have wheels for meanwhile,on thursday,fridy. The next monday,tuesday,wednesday and today on thursday 12-02-2015 i had to phone barloword to find out what is goin on,they just said they will phone me back since last week wednesday up to today. No respond at all. The service is the most poor service ive ever seen or experienced. I try to look after my vehicle to let it last for many years,who is to blame if my vehicle fails because of this?