I was approved with a 1k credit line and needed to spend 5k.. A day before the deadline I called them explaing that i can't finnish the spend because of the low credit line.. I was just a few hundered short of complete.
They opend a case and later credited the miles, and then I somehow managed to complete the spend on final day.. And got an extra 30k 😀
This was for the Lufthansa card, but don't think it makes a difference.
So definitely call and have a good reason for missing the dealine, and maybe they'll credit you.