still getting paid ESA after transferring to UC

I have recently migrated to UC however they are continuing to pay random ESA payments. I attempted to phone them which is really difficult for me and was shut down by the operator not allowing me to speak which led to me losing my temper and putting the phone down. I subsequently wrote a letter asking them to update their records to reflect I had transferred to UC as the system was still showing me as receiving ESA and thus affecting my UC payments. Several days after I had sent it I received an ESA payment and now again today I have received another ESA payment both of which are for £281.10 which seems to be around half of the rate I was initially receiving.
I just cannot deal with trying to phone them again and clearly the letter didn't work and I just dont know what to do as I suspect I will now have those 2 payments deducted from my next UC payment. I managed to put the 1st payment aside in preparation but im already struggling to manage my finances having moved from fortnightly to monthly payments and my mental health means I frequently overspend and I have no support/friends/family that can help to sort out these incompetencies.
Call me cynical but I can't help thinking they are doing it on purpose to see if I try phoning because I have said I can't manage phonecalls and exactly evidenced by my losing my temper when I tried initially. All it is doing is making me really angry and causing significant psychological trauma.

I would be grateful of any advice many thanks