The answer to your question is maybe. What you need to do is call customer service and ask for customer relations. A customer relations agent can look at your account, and may offer a receiver for a reduced cost (possibly free), or offer you credits on your monthly bill.
It is dealt with on a case by case basis. They will look at account history among other things.
Note that you will want to have either a 605 HD receiver, or a 630 HDPVR. The 505 and 530 models will not be able to tune HD channels at some point in the future when Shaw Direct moves to MPEG4 compression.