It seems this is Scottish Power's fault and your consumer rights may have been breached.
Because the dispute is with a gas company (SC), you can avail of the Ombudsman scheme here - which should resolve the dispute. It is free to use and quicker than court action - you have to first make a complaint to the energy company, wait for their final response and then go to the Ombudsman. The initial complaints should take up to 8 weeks and the Ombudsman can take up to 16 weeks for a decision to be made.
In the meantime you should dispute any bill you may receive as this is not your fault. They should not take any enforcement action for the duration of the complaint investigation.
You now have to make a formal complaint and if that does not resolve the matter ask them for a "deadlock letter", which is a letter giving their final response.
The complaint to Scottish Power can be made here: https://community.scottishpower.co.uk/t5/Complaints/ScottishPower-Complaints/ta-p/37
Once you have the deadlock letter the next step would be to escalate this to the Energy Ombudsman - they will investigate and liaise with the energy company which would hopefully result in a resolution and you should not be out of pocket. They can order the energy company to make a financial award for inconvenience if they have acted poorly. My view is they have acted poorly as they told you the supply would not be transferred, which was clearly not the case.
The service is covered by the Consumer Rights Act 2015 so you have a right to expect a reasonable service which is carried out with care and skill - if you do not receive this then the regulator will step in but it also means you can sue for any damages or losses incurred as a result of the energy company's conduct.
Once you have SC's final response and assuming they do not resolve this, you can complain to the Energy Ombudsman by email here: *****@******.***
Or via their website here: www.ombudsman-services.org/energy-complaint.html