Write to address on contract -
- Use the specific term "unsolicited goods and services";
- Refuse to accept the contract;
- Insist that they are liable for return of their property ....
AND
- if not collected after (say) 30 days, you will be forced to charge for safe storage until they do collect.
It's a bad old con, known as "inertia selling" and is covered by the "Sale Of Goods Act" (see
HERE for details).