Your first contact was probably via their contact page...is that correct? Now you have an email from them that you can reply to unless they said not to. If you can reply, then definitely send them an email. Also, make sure that their reply to you did not go into any SPAM folders.
If you have to use the contact form, then you might get someone that is different from the last person and re-start the process.
I'd think that you should contact them if you're sure that it's been over the allotted time for the RMA to come in.
Dave