Sky is asking me to return equipment I do not have

[RobGWxm]

I recently switched to Stream and returned my Sky Q box as requested.   Sky is now asking me to return a Sky Mini Box,, which I do not have.   I did have one several years ago but that was returned long ago when I cancelled my multi room.   How do I ge this request cancelled please before Sky tries to charge me the £52 for non return as per their email.  I've tried the virtual assistant and got nowhere, the email says I cannot reply to it, and I am reluctant to spend a long time waiting for an agent to be available to resolve an issue that is not of my making.  Any advice please?

[caesarome]

@RobGWxm 

Have they actually asked for the mini box or have you been sent the standard email which mentions all the possible equipment that they would like returned ?

[RobGWxm]

Yes they are specifically asking me for a mini box, "to avoid being charged £52"  but a quick check on my billing history would show that I have not had this, or been charged for this, for several years.