I find that calling the GP number always routes me to an East (SABRE) rep. If I want to reach a West (SHARES) rep, I call 1-800-247-5691 which is apparently the West version of Dividend Miles customer service.

I actually prefer dealing with the East reps, even if it involves booking the US 8xxx flight numbers for HP flights, because for some reason West/SHARES does not properly accept Canadian credit cards and billing addresses. In order for them to get accepted on the West side, someone has to call MasterCard to process the transaction manually. I hope this problem gets solved before US completely switches to SHARES!