A belated warning regarding scammers which pose as subscription renewal services. One such outfit hit F&SF last year:
In short, be suspicious of any renewal offer from a third-party company. Names that appeared on the mailers:
Magazine Payment Services
PBE: Publishers Billing Exchange, Inc.
Readers Payment Service
The thread above provides more info on this particular instance and subscription scams in general (including what to do if you get caught by one).