Do not unlock your iPhone until you read this!!
Do not go to Wondershare .com - they cannot help you unless you have your AppleID and password and then you do not need them anyway!!!!
Definitely do not go to officialiphoneunlock .co.uk - they are nothing to do with Apple and they charge £20 up front that 'cannot' be refunded even though this is against UK law. Of course they turn out to be overseas and beyond the reach of UK law.
Now that Apple has so much power over consumer and business it is important to be vigilant with company phones. Now that users can activate 'find my phone' and effectively turn an iPhone into a paperweight, you must be sure that they unlock all phones in person as they are returned and that you are able to remove 'find my phone' before you accept the phone back. I would recommend that you put a deposit on all company iPhone in lieu of wages, and to avoid any confusion that you keep all bills with the IMEI numbers of new phones as this is the only way that Apple will unlock them.
If you have the computer that the iPhone or iPad was backed up to then there are software that can help you available on a home user basis such as Elcomsoft phone breaker. These softwares cannot break into the iPhone but can break into the backup in order to recover email addresses and passwords. The iPhone backup can be encrypted though, so watch out for that. Either way the software even for a home user version is not cheap. Best just to dig out the original phone bill and send it to Apple with the IMEI number on.