Had oil changed, radiator flushed, and belt changed, now no AC

[Rong]

I went to a place where I have been going for years to have my oil changed this AM, and they flushed my rad, and told me my belt was cracked, so I let them change it. BIG mistake! Left thher place turned on AC and hot air! It was blowing frosty this morning when I got there. They said coincidence, I said no way. What can I do? Compressor is sporatic now, and no cold air.