It's so awful to have to wait longer than you were originally told and I'm sorry this happened. As long as you meet all the qualifications and submit your request, it should go smoothly. In the off chance it doesn't go through like it should, we do have ways to escalate it internally on our end. As long as everything matches up, you should have to repeat the waiting process another time.
I also have the same issue on an iPhone BOGO offer from Dec 2017. I first used the website Customer Support messaging to find out if I qualify for the offer. Wasn't able to get an answer after a few attempts so I called 611. I explicitly asked to let me know if I don't qualify or if there would be any issues as I don't want to be in a position of getting denied the offer and I was told that there were no problems with me getting the rebate as long as I submit it.
After submitting the rebate on Jan 2, 2018, it took more than a month (I found out the status this week) to find out that it was denied because the plan that I'm in does not fall under the promo. What??? I'm now stuck with close to $2k bill (2 iPhone 8 Pluses) that I would not have incurred if I was told the truth. When they transfer me to the rebate hotline, they get me to a juncture where they ask if one of the reasons was that my plan doesn't qualify. If you answer yes, the canned response is to upgrade to a qualified plan. Textbook BAIT AND SWITCH. Not only that, I even opened up a new line to "qualify" for the promo. I really need help as this created a financial crunch now for a very long time customer.