[Solved] CMS...cause for concern?

1) I had a periodic income check recently as requested i sent in most recent 5 payslips
2) After 8 weeks and a couple of calls chasing it up, i received a call from the CMS but wasnt able to answer due to work. The case worker left an answer phone message stating they had done the calculation and there was no change to liability. And that i would receive a letter to confirm
3) waited 2 weeks. no letter
4) rang CMS , spoke to 1 of the many clowns...told for some reason it appeared letter wasnt issued and would re -issue it.
5) another week. still no letter
6) rang back...spoke to another female operator who seemed to understand. And issued a letter
7) letter received but upon reading it, it read as though there was a change and that i would be sent the payment plan confirming the payments in the post
8 ) so i rang up again stating...the answer phone message said there was no change yet the letter implying they will be sending me the payment schedule
9) person on phone read the case notes and copy of letter agreed and said it appeared the wrong letter was sent out. as it sounded contradictory, and would note it on the system
10) so i sent in a written complaint (only been 8 months since my last written complaint) highlighting the above issues and asking to rectify by sending the correct letter. Reason i was being picky about letter is because of their reputation i wanted decision in writing to avoid future issues.
11) after 4 weeks (despite their terms stating complaints will be dealt with thin 14 days). no response
12) rang up again , they told me letter my received 16/02 and case worker would call me next day
13) two days no call back, so i rang myself on the second day and did get a call back later the same day...the case worker this time said that after reviewing all infomation, the letter sent was correct , but the wording admitedly was confusing as they are all done off a template on the system and not individually typed up.

I asked why it was so difficult to type up a sentence to the effect of "we have reviewed your payslips, the outcome is there is no change to liability until your annual review".
She said we dont issue individually tailored letters.??
But i thought all cases are unique with different circumstances..

She confirmed there was no change in liability and that the amount quoted on the most recent letter as being the amount the calculation/liability will be based on was exactly same as the amount from the annual review letter so as the two amounts were the same, this indicated on the system that there was no change. She said there was nothing to worry about and the letter was correct.

I noted the name and date/time of call

My only worry is that reading up on the nightmares people face over ghostly arrears suddenly appearing , i dont want this to come back and bite me..

I have all documents and call logs and saved the answer phone message.
will this be enough to cover me if any "very common errors" pop up in future and they say i owe xyz to due this calculation?