Complaint Review: MTG PROCESS SERVERS

I hired them to serve paperwork to a certain address not affiliated with the court address of record. They served and all was well however the court didn't recognize their service. After a couple months I paid to have service again and they assumed to serve on the court address of record instead of the address I provided and initially hired them to serve. When I contacted them about their assumption I was told I didn't give specific instructions and they just served the address on the court papers. I didn't need private processor to serve what the Sheriff's office does. I paid them to serve a second address. They refused to serve the address I provided unless I paid a third time. I asked them to reconsider however they refused.