Hmmm strange??? Ive never ordered anything from them via mail order but i have purchased stuff off them a few times at shows. I have also met Mike Rosser - the guy that runs it - as well as discussed a few things with him on phone. He has been very helpful and friendly with me in the past and i would say that your experience is a rarity. From what i gather MRM is a part-time thing to Mike as he has a day job, so this maybe why u are having a bad responce to emails etc - although thats not much of an excuse!
There is another MRM site -
http://mrminternational.future.easyspace.com/ where u will find an alternative email address - try this. Both sites have not been updated for ages and i often wonder what he's playing at, but i know for sure he is still trading and replying to emails because i had a responce from him a few weeks ago.