Just to summarize these are your two main gripes. (1) The mod arrived damaged and you were able to fix it without a replacement offered by Lermod? (2) The mod was designed to work with the game prior to a code change from Stern. Lermod had no control over this, but still offered a refund anyway? Lermod should post the impact of the code change on their website with the product information and possibly stop selling it altogether.

Its sounds like they have been very fair with you. I am not sure what you expect from them. I have several Lermods installed in my games and have been completely satisfied with the quality and support. When you mod a game using a nonfactory part you assume a level of risk. The risk is you could damage the game during installation, void your warranty or the mod could stop being functional due to code changes the mod maker has no control over.