Child care vouchers fail
In the UK it's possible to take a small amount of your salary as child care vouchers tax free. The idea is that the vouchers can then only be spent with recognised child care providers.
Your employer must register with a voucher scheme, and your child care provider must be registered with that same scheme.
Unfortunately there is more than one scheme and no way to transfer money between them. This means that every child care provider has to register with multiple schemes, and if they're not registered with the same scheme that your employer pays into, you can't use your vouchers with them.