Problem with payment,

when paying with the card, sometimes it works well and returns a success message, but then sometimes on the second third try it returns an error message and money is cut off anyway…(mail is not sent after that because it works on success only.
what May I check?
asked bank which api we use and they say payment is correct.

debug log says

[2020-09-18 07:28:35] main.INFO: TBC Auth Request {"request":{"command":"v","description":"firefox-3-2000000097","currency":"981","msg_type":"SMS","language":"GE","client_ip_addr":"162.158.210.153","amount":1}} []
[2020-09-18 07:28:36] main.INFO: TBC Auth Response {"response":"TRANSACTION_ID: KZ7nK1sKgVwB18CNPDKMc3K9cLA="} []
[2020-09-18 07:28:57] main.INFO: Post value {"postValue":"{"trans_id":"KZ7nK1sKgVwB18CNPDKMc3K9cLA=","Ucaf_Cardholder_Confirm":"0"}"} []
[2020-09-18 07:28:57] main.INFO: trans_id {"trans_id":"KZ7nK1sKgVwB18CNPDKMc3K9cLA=","encoded":"KZ7nK1sKgVwB18CNPDKMc3K9cLA%3D"} []
[2020-09-18 07:28:58] main.INFO: Payment response/status {"response":"RESULT: FAILED
RESULT_CODE: 908
3DSECURE: NOTPARTICIPATED
RRN: 026207208959
APPROVAL_CODE: 200169
CARD_NUMBER: 4***********8987","status":200,"trans_id":"KZ7nK1sKgVwB18CNPDKMc3K9cLA="} []
[2020-09-18 07:28:58] main.INFO: Payment failed or has been cancelled [] []