Hi,
Sorry about the frustration you experienced,
Please confirm, that you received reply from support, because I can't see any email without an answer.
And since it happens pretty often now, let me explain the root of the problem.
This is an issue with coinbase payment frame, they round the amount to 4 decimals for display purposes and then sometimes don't mark such payments as successful.
Check this screenshot:
Amount to pay is 0.0026, but if you hover mouse over link or QR code you can see in the browser left bottom corner real amount 0.002593, which has to be paid.
We're in talks with coinbase engineers and they promised to fix the problem. Please hold on until then.