FNB The ultimate nightmare experience (brain cells on lockdown)

Trying to get a +40 day debit order reversed at FNB is the ultimate nightmare. After submitting a debit order reversal form on 19 March as instructed by an Agent in their Debit order reversal form, I was advised to submit the request on the app, after daily following up with them. Trying to do the reversal on the app is a total nightmare. I spent the last hour on both my mobile device as well as Laptop with my banking profile being open on both devices, but could still not complete the request as the device is an "unverified device". Don't know what else to do as their so called customer service is one of the utmost *********** useless customer service departments to deal with. The Agents insist that I do it on the app, being very inconsiderate & insensitive to the fact that it's almost 3 weeks since I submitted my request....seems like FNB's phones are also on lock down as none of them bother to pick up a phone & call me..........