As you say, this is expected but it is no less awful for it. In fact, probably all the more awful as a result.
I appreciate your concenr and sensitivity for the legal issue but I wish I knew the name of the producer. What manufacturers fail to realise is just how effective the grapevine is. If you were to tell us that the paint you used was of brand XYZ then the manufacturers would, at least, be able to put forward their argument. As it now is, due to the possibility of prossecution, you keep quiet but the information spreads by word of mouth - something the manufacturers have no say whatsoever over.
I hope the problem is soon resolved for you. What next? Will you be taking legal action?
Aye // Stephen