Network connection problem after battery replacement

Hello, I hope you are well. According to the attached invoice, I ordered a replacement battery.s21ultra I went to Samsung repairs in the Mall of the Emirates, Dubai.Upon delivery, before paying, I noticed that the phone was not connected to the network and was experiencing disconnections and reconnections. I informed the technician that they were trying to fix the problem. But in the end, they were unsuccessful and said that they only changed the battery. there is Technical a problem and we are not responsible for this.I told them that I delivered my mobile phone to you safely, but you Broken it. Considering that I was planning to travel the next morning and I had to leave the place in the last minutes of working hours.Since that day, I have emailed the store’s complaints department 3 times, but unfortunately I have not received any response.
already I’m out of Emirates ,please advise me How do I pursue my complaint about this offending unit?

Dear @Nima_Nayeri

You should first escalate this formally to Samsung Gulf since the Mall of the Emirates store has not responded. Lodge a detailed online complaint (with invoice, job sheet, and emails) via Samsung Gulf “Support/Contact Us” and ask for an investigation into damage caused during battery replacement, as you are now abroad.​

If unresolved, file a consumer complaint with Dubai Consumer Rights (online complaint portal requires invoice and trader details) explaining that the device was handed over in working condition and returned with network failure.​

If still need help, reply to us.