The unauthorised use of software or services which can unlock devices, such as mobile telephone SIM cards or which enable access to restricted areas, confidential information, other encoded data or protected data procedures, is illegal in the UK.

eBay's policy on unlocking software:

Software or services which can unlock devices such as mobile telephones SIM cards or which enable access to restricted areas, confidential information, other encoded data or protected data procedures may not be listed on eBay

Community Watch
eBay Community Watch - Community members can report prohibited, questionable and infringing items to eBay.

If you have any questions, please contact customer support.