Ian, the information is all in the setup guide and the upgrade guide.
It is very easy to perform your own upgrades - you do not need a consultant to do it for you. But you must do the upgrade on a test environment first and take database backups as you go along as the only way back would involve a database restore. Test the results from the test upgrade thoroughly - I always need to do a bit of work to make sure that the upgrade does not inadvertently change behaviour that I do not want.
It should be TPSERVICES
Just in case it could also have been changed, a quick look for this line in the tps.config file would reveal?
<add key="Password" value="tpservices" />