cashback and contacting customer servies

[#1]

Came through to plusnet via a cashback site and completed the whole process on-line for both phone (payed for line rental in advance) and unlimited broadband, unfortunately i am having issues with the MACcode given to me by Sky and inputted online during purchase.
i have contacted online support without any any reply  since the 14th September, i then contacted customer services by phone and after 30 minutes on hold!! got through they advised i get a new mac code which i did and put it through the on-line help request thing, its been 3 days still no reply!!
i have 3 questions
1. If i now contact customer services by phone and endure the agonising wait and give them the new MAC code, will my cashback claim be declined? 
2. If this is the level of service i can expect before i have even joined is it worthwhile joining rather than cancelling and staying with the devil you know, especially if the cashback (one of the main reason i joined) doesn't come through!
3. If i cancel do i get refunded the  line rental i paid in advance? and how long do i have before i can cancel?
Many Thanks in  advance for any help.

[#2]

To answer number 3, quote from Plusnet's website -
"You can cancel Line Rental Saver within the first 14 days after ordering and get a full refund. After this, you can cancel the service at any time, but the fee is non-refundable."
No.2(first part) - probably. They've taken on too many customers without increasing their staff numbers sufficiently.

[#3]

Thanks newagetraveller.
only question number 1 to go  🙂

[#4]

My experience may help answer your query 1.
I signed through TopCashback and Adam Cassim then changed dates and rates for me. I was still paid the Cashback promptly and exactly as was quoted by TopCashback.

[#5]

Good morning everyone,
Everybody's answers are pretty spot on here, however I'll answer from our standpoint so you have something quotable from a staff member:
1. The claim shouldn't be denied. Once you have signed up via that process, then it's a done deal and you should definitely get your cashback.
2. I'm sorry that you had to wait some time to speak with us. I have checked your account and can see the MAC key. I have gotten one of the provisioning experts to place the order for you now.
3. The rule is 14 days. But subjectively, I'd say you can get the Line Rental Saver refunded as long as we don't activate either your broadband or your phone.
Hope this clarifies for you, and sorry again for the long waits you've had to suffer.

[#6]

Excellent, you all have been so helpful thanks.
Broadband is due to be activated next Monday woohoo.