Tax Free Childcare

My account finally got set up after waiting 12 weeks, and I was told by the advisor on the phone that if I sent in an invoice from nursery, I would be reimbursed the 20% costs for that time (approx £700 in my case)

I've sent in the letter and invoice (got proof that they signed for it), just wondering how long it might take to get that money back? If anyone else has had any success etc