Q: Bad mechanic issues

I went to get a simple oil change and l asked the mechanic to look at my ac b/c its not working. He gave me an oil change and said that he had to recharge the ac and use dye to find out l needed a new compressor. A day later my engine light is on l go back to the guy he says my engine is overheating because l need a new coolant temp & therm housing w sensor. I go get a second opinion at a dif. Place the mechanic there tells me that l do need a new therm housing unit but also that my radiator overflow tank is full of oil and what looks like dye which caused my therm to fail. What should l do l think the first mechanic botched the job and dumped dye in my radiator tank. Its full to the top w gunk. I just had a tune up in January and a engine & transmission flush last june. No way should it look like this. Now l cant even drive my car until its fixed. What should l do??

My car has 75000 miles.
My car has an automatic transmission.