If your daughter has missed some mortgage payments the mortgage provider has probably obtained a possession order (not a suspended possession order), often for 28 days time, your daughter probably did not file a defence but this does not mean that your daughter must move out on the date given for possession
The mortgage provider must now return to the court and obtain a warrant for possession, which will permit them to have court bailiffs present to remove your daughter (and others) with their possessions from the property. The key is now negotiation with the mortgage provider, probably the reason they rejected your payment was they gave your daughter a date by which payment had to be made and it was not received by that date. Talk to the mortgage provider, if further court action is taken try to have it transferred to your local county court and attend and explain the position, it will be very informal, in a room, the judge will not be robed and should be addressed as Sir. Alternatively consult a local solicitor with housing experience.
Just completed this and then I read your further post, you need to get the warrant suspended, quickly.