Leaking soap drawer/dispenser

Just moved house and reinstalled washing machine – normally there’s two taps and pipes (red/blue), but in this house there was just the one cold-water pipe and tap with a Y-shaped fitting to which I’ve connected the two hoses.

Now when I switch it on water floods out of the dispenser at the top, unless I put it on a basic economy setting, and then the water doesn’t come out and it works OK (not necessarily as a result of what I mentioned in the first paragraph, just thought a bit of background might be helpful!).

Anyone know what the problem could be? Machine is a Hotpoint WD64 washer/dryer by the way.