I've posted a few comments in a number of threads, saying sorry for the fact comments are taking a long time to post, and that 502 error messages are so common.
Please accept my apologies.
I wish I could advise on what the problem is or what causes it or better still when it will be fixed. I can't. I'm sorry. I'll hold off from posting more until we have some answers. No point in cheesing you off.