Enforceability of a verbal contract

Over the telephone, I agreed to sell my private number plate to a company. I was grieving as i had just lost my husband and it was his number plate. The person on the telephone did tell me that I was entering into a verbal contract. I did not know what that meant at that time. I now do not want to sell the number plate and they are saying that I have breached the contract.

Is this correct? What are my options?

Alasdair Taylor's answer to Enforceability of a verbal contract (1429694207)

Answer to the question: 

There are various English law doctrines which affect the validity and enforceability of contracts. None of them springs to mind here.  Without more information, however, I can't with any degree of certainty say whether this is or is not a valid and enforceable contract.

One factor to bear in mind is the value of the number plate: the more valuable it is, the more worthwhile it may be for the buyer to threaten and pursue legal proceedings.