need help from everyone

basically I have done two Samsung imeis with somebody from this forum. paid via PayPal as gift. (bad idea probably)
anyway
1. I have send him two pictures in recovery mode to check can it be done. (g930f and g935f)
answer yes
2. paid via PayPal
answer all ok
3. he done two phone.

Problem. those two phones now see as dual sim (g930fd and g935fd) I was able to flash g930f using g930f firmware but DRK problem. solved buy rooting phone which by pass drk checks but than I have a lot of app crashing etc.
g935f can not flash, can go into download mode but not able to flash hidden.img problem. do not want to put ******* kernel just yet.

So need your advise how can g935f (single sim) after imei "fix" turn to g935fd (dual sim) ? he put wrong cert for my phone? if so I should be able to get refund? or at least ask to help to resolve?

P.S I ask help from him, but he send me link to easy-firmware, also now he is sick busy or eating 🙂

P.P.S those two Samsung are from o2 and Vodafone uk they do not sell dual sim Samsung s7

so my question is if he messed up my phones? yes or no, if yes than I will disclose his forum id and will ask for refund and will make other gsm brothers aware of him. just need independent opinion on this.

thank you