No its not possible to convert the unit to a different model number, there are work arounds to add certain features by putting a custom menu on it but that might not address the speed camera warning issue.
Having read through your other posts it would appear you have been given a load of poor advice by TomTom Customer Support. I would phone them again on Monday and ask them to either honour the device specification as advertised with operational Saftery Camera W\arnings or offer a full refund, point out it was their own advertising media and their Web Site specifications for the device you purchased are wrong and the device does not meet the capability for which you purchased it. If you get nowhere with the first person who answers the phone request to speak to their supervisor - Mike