Approved $400 refund for unapplied Mobile Select promotion — CSA callback never received, requesting resolution

Posting here as a last step before filing an FCC informal complaint, since I've exhausted chat/phone support and a confirmed CSA team callback never happened.

Summary
I signed up for the "Mobile Select line free for 12 months with Xfinity Internet" promotion on June 1, 2025. The promotion was successfully applied at signup according to Xfinity's records — this was confirmed by a chat agent on May 16, 2026, who pulled up my account history and verified the original enrollment. However, the monthly bill credit was never actually posted to my account, and I was charged the line fee for 10+ consecutive months totaling approximately $400, paid out-of-pocket on the credit card on file. (Total payments so far: $450.96, plus $42.41 auto pay coming up 5/22)

What happened on May 16, 2026
After a >90-minute chat session, the agent confirmed the signup, validated the charges, and escalated to Tier 2. Two tickets were opened:
ECM0021920883 (initial escalation to Tier 2)
ECM0021921311 (Tier 2 escalation to upper team)
The total approved credit was confirmed as $400. Because the amount exceeded the agent's authority, the case was routed to the CSA (Customer Service Adjustment) team, and I was told CSA would call to finalize the resolution — specifically the refund method, which the agent could not change.

The unresolved question: refund method
During the May 16 chat, I clearly stated and the agent acknowledged the following preference:
Primary: refund to the original credit card the charges were paid on
Fallback: prepaid Mastercard
Not acceptable: credit applied to my Xfinity account
Account credit doesn't work for my situation because the Mobile Select promotion is ending shortly, the mobile line will be cancelled, and I haven't committed to remaining on Xfinity Internet long-term. Applying $400 as account credit makes me wait many months and depends on my continued tenure as a customer to draw down a refund of money I've already paid out-of-pocket.

Status as of today
It's now been six days since the May 16 chat. No CSA call has been received. No email follow-up. Both tickets appear closed on my end without resolution.

What I'm requesting
Confirmation that the $400 refund is still being processed
Refund issued to the original credit card on file (or prepaid Mastercard as fallback)
Written confirmation via email of the resolution method, dollar amount, and timeline before the case is closed

Evidence available
I have the full chat transcript from May 16 saved, including the agent's confirmation of the June 1, 2025 signup, the $400 approval, and the handoff to CSA. Happy to share via DM if needed.
Could a member of the support team look into this and confirm next steps? I'd prefer to resolve this here rather than escalate to FCC or the Texas AG, but I'm prepared to do so if the case isn't actioned.