I have had a money market account with GMAC for years. Recently, I have opened several CD's with them because of their 4.10% yield which is pretty good for a 12 month CD. The rate changed today but I was lucky to open my last CD yesterday, so no problem.
I have not had any problems with GMAC and I do my transactions on line on my money market account.
If you want to avoid the long wait time on the phone, you can email GMAC in your account (private email) and give them your instructions. They respond within 24 to 48 hrs.
Jeannette