Hi there. It sounds like you are in a difficult position. More information about your situation is needed to properly assess your legal situation, but the general information below may be helpful.

Copyright refers to the legal rights a person has in new work they have created. This work is usually of a literary, dramatic, musical or artistic nature. Copyright provides automatic protection for its creator by giving that person the right to assign or licence their work to another person. Copyright does not protect ideas, concepts, styles, techniques or information. However, these things may be protected by other types of intellectual property law. For example, a planning drawing may be deemed a ‘Design’ which is capable of registration and protection under law.

In your situation, the exact nature of the intellectual property rights contained within the design drawings will determine what rights its creator (the design company) can claim over the drawings. Your rights will also depend on who signed the original sale contract. If the sale contract for the property was between only you and the vendor (and not the design company), it is unlikely that the design company can now claim money from you for the drawings. However, this will be subject to the exact terms of the contract, which may specify payment arrangements.

Furthermore, if there is any indication that either the vendor or the design company acted improperly or fraudulently in their dealings with you, you may have legal rights against them to either seek compensation or withdraw from the contract.