BMW service does not resolve car issues

I sent in my Mini Cooper to BMW Somerset West to fix 4 issues with my car which I mentioned to them when I was booking in my car as well as making a note for them when the car was being collected for the service. The car came back with over R10k bill and none of the 4 issues were resolved. I was actually really tight for cash and only wanted the 4 issues looked at but nevertheless. The car came back with none of the 4 issues resolved. I have sent my car in since then about 3 more times. The issues are still not resolved. The coolant leaking was 1 of the 4 issues. The coolant continues to leak until now. I asked bmw to contact mini to ask them about the leak and all they said to me was that they are an approved Mini dealer. With the last send in of the car, I got the following response – the coolant leak was caused by an airlock in the system. When I email to find out how that caused a leak I got no reply. Emailed again and still no reply. Wrote to Mini themselves and got no reply. So Bmw ....Is this a permanent leak then, will my garage floor have coolant leaked on it forever? Will I continue to have to fill the coolant cause it leaks and leaks and leaks. Follow up Customer service???

And as a side comment, I needed bmw emergency assistance some years ago and when I called the number, it just rang and rang and rang….