What's the best VS address to send a letter to?

Given that I made 80TPs last year, I've finally got organised and am about to send a letter with my questions around whether the 80TP upgrade could be used as a 1-way upgrade for 4 people (i.e. only way I'll ever get any use out of it).
Question is, what's the best address to send it to so that it will get the 'right' level of focus on it? If simply sending it to dunstable means I'm likely to get a stock reply from a junior rep, I'd rather bypass that...
Any thoughts on what has worked for people in the past would be appreciated...
thanks
RC
Question is, what's the best address to send it to so that it will get the 'right' level of focus on it? If simply sending it to dunstable means I'm likely to get a stock reply from a junior rep, I'd rather bypass that...
Any thoughts on what has worked for people in the past would be appreciated...
thanks
RC