Vw Service Cost me 5 Trips Back!!!

I have a polo 2011 Model. It has always been serviced at McCarthy Vw . Car has a full vw service history. Due to convenience i decide to change dealerships to have car serviced . Firstly they broke my engine cover when replacing plugs. They acknowledge this and called me in to replace. Thn it came 2 my knowledge that they removed my wheels(god knows for what) in a 60000 service and did not put back my locknut. They called me in once and tried to find a matching locknut to my set and could not. So thy told m 2 cum bck anotha day wen they replaced the set. few days ago i noticed on my driveway tht my car is leaking oil. Then paid a local fitment center to put car on ramp to investigate. we saw that the oil seal cover has a small bolt that was over tightened and now has a crack on it. So oil is seeping through and has messed the entire engine bay with oil right down to the sump.I call the manger last Tuesday who said they will have to order a new one. this Tuesday after receiving no call back as promised. He told me he will call back . He calls back and tell me they dont open the seal and cannot replace it. call vw south africa they got manager to call me again to tell me he wont!!!