Billing Dispute

Hello,

I returned my directv equipment sometime back through The UPS Store.  ATT has sent me a final notice to pay 149.99 for equipment.  I've gone to The UPS Store to see if they have record, and apparently they send all deliveries in one large box and do not keep record...  I tried chatting with directv to see if they have record of the returned equipment but they refer me over to ATT.  ATT has taken my complaint but they say there is no record thus I must pay the bill.  Any recommendations?  Thank you.