Auto body repair & detailing: 1989 BMW rear wing, bmw m3, epoxy primer

Question
I have a 1989 bmw m3 with a factory rear wing on it. The problem I have is that it has bubbles appear on the top about eight months after it is repainted. A very good paint shop that does BMW work for dealer in our area has painted it three times. Each time they stripped it down. They think it is releasing gas from the plastic. Please help

Answer
Edward,
 
We appologize for the delay in answering your question, we have been having trouble with our email.
  Ask the body shop if they are using a plastic primer on the part before base and clear coat.
  We would suggest asking them to use a plastic primer and then use an epoxy primer.  Then they can base and clearcoat.
Thank you,
Mike and Lisa