No response to account payment updates

I had a rough year last year and my account was handed for collection. I battled by kept to my agreement every month with collection department. Once things were starting to look up again I requested a settlement amount from wonga, and asked that they please update my last payment which was still not reflecting on their side after 2 weeks. I send the proof of payment as they requested for the previous installment not reflecting on my account on Friday 14 February. On Monday 17 February I paid over the full and final balance outstanding and mailed the proof of payment once again to both wonga and the collections agency. I requested for a paid in full letter, but received no reply whatsoever from wonga. I tried to phone them on Monday 17 February at 17:15 as their website state their operating hours are from 8:00 - 18:00 but there was no answer. I tried 9 times without any luck. I then tried the ***** line as this was the only other line on their website, but this number does not exist. I emailed the proof once again to all parties today 18 February, and still I have not received any feedback whatsoever for either payment of 30 January not reflecting or Monday 17 February not reflecting. I tried phoning them again 12:24pm and held on for 30 minutes, without any answer. I phoned the collection agency and they said all payment are updated on their side and they have requested paid up letter from wonga but did not get response from wonga as yet, and that I should follow up with wonga. I am now sick and tired of sending emails and phoning non stop and not getting any answer for a paid in full letter. They are very fast to send you a bill but they cannot update your payment and confirm receipt thereof.