Motorola and Tomtom Bluetooth

I was just hoping someone here was knowlegable of my situation. My Motorola V551 phone used to be compatable with my Tomtom 910. After the last update to my 910, I can't get the TomTom to recognize my phone. My phone still has the 910 listed in it. I have an unlocked Cingular V551 that I'm using with T-mobile prepaid service. TomTom support first said my phone was supported (which I knew, because it was working with it), then, said it never was compatable, being T-mobile. Then, said if I was using Cingular service, it would be compatable. I think it's their update that messed it up. I'm afraid if I change to Cingular, it still won't work and TomTom still won't say it's their problem. I was just wondering if anyone had any suggestions or knew what I could try. TomTom don't seem to have a fix for me. Thanks.