Service order pending since last one month, Customer support not replying, What to Do ??

You'll have to contact support again
support.xbox.com/.../contact-us they are the only ones with the details of your repair,no one on the forums has access to that information.

Still not fixed and it's been 3 days since I last heard anything back from support.

Customer service? What customer service!

Hello Popticgamerzz11,

We only schedule a deposit automatically at 5000 or more pending Credits. Since your pending Credit amount was beneath this amount, it had not been scheduled. If you would like to request a scheduled deposit, you may do so once you are at 1000 or more pending
Credits. There will be a button on your MyRewards page.

We do deposits twice a month. Once at the middle of the month, and again at the end of the month. Additionally, it takes one deposit cycle to process pending Credits. Since you only hit the 5000 pending Credit amount after last months mid-month deposit,
it was not available in time to be scheduled for last months end of month deposit. You should expect your deposit to be processed and deposited by the mid-month deposit this month.

Thanks everyone for your replies, I talked to the support team in Mexico and they mentioned that the email I received was self-generated due to the time that passed since I placed the order (1 month). The service order is still active in their support and
repair system.

Hello GeeqShuq,

Pending Credits require one deposit cycle to process. A general rule of thumb is Credits pending on the 1st through 15th will be deposited in the end of month deposit. Credits pending on the 16th through the 31st will be deposited in the mid-month deposit
the following month. Since your last pending Credit event that triggered the 5000 pending Credit amount required for an automatically scheduled deposit occurred on the 19th of last month, your Credits will be a part of the mid-month deposit this month.