Bad business practice

I had a the c-way wireless internet services for 3 years. On inception of the agreement, I bought equipment work R2500 with a promise of a warranty on it. 4- 6mtns down the line they upgraded their systems and came and upgraded the equipment at my house. They never told they were loaning me the new equipment, they also never gave me my old equipment back. I assumed that this was still under the agreement made initially. Now 3 years later after cancelling the services, they debited my account twice after cancellation and still say they want their equipment back and they kept my old equipment in their storage of which the warranty is now void. How can trust that it's still the same equipment, why did they not give it back to me?