Payment Issue - amount mismatch

[NikkiK1234]

I've been in touch with Virgin many times over the last month trying to fix a contract expiry / discount mismatch. Last month I spoke to a member of customer retention (3rd attempt of getting fixed after unfulfilled agreements) who offered to have the discount issue fixed and told me she had applied a credit to my account to bring the bill down to it's usual level while it got fixed. Bill came out at the usual level as expected, didn't think anything of it. 

Today I've received an email stating I owe the higher amount plus the "amount underpaid" from last month and a late fee.

I pay by direct debit so Virgin should have taken the full amount they wanted if the agreed credit wasn't applied and then I could argued out the rest. I've raised a complaint in relation to the contract/discount issue but I'm now panicking that this underpayment will mess up my perfect payment history on my credit score. 

Has anyone experienced similar that can reassure or offer some advice?

[MOD EDIT: Subject title changed for clarity]

[Akua_A]

Hi @NikkiK1234 

Welcome to our community forums and thank you for your first posts.

Sorry to hear you have been having some discrepancies with your billing. We can understand the inconvenience caused and we want to best help. I can see you very recently contacted our team about this issue. Was the issue resolved with our team? Do you need any further help with this?

Thanks,

[NikkiK1234]

Well after two hours on the phone last night being passed around from department to department I've had it escalated to a manager and should get a call back early next week so we'll see. 

[Steven_L]

Thanks for coming back to us NikkiK1234, I hope that you can get your issues resolved on the arranged call back. Please let us know if you need any further assistance.

Kind Regards,

Steven_L

[NikkiK1234]

Hi Steven, nobody called me back... Again. This is beyond ridiculous now. I've spent over 3 and a half hours in total on the phones over this issue and now I'm going to have to call again.

[Tom_W1]

Hi @NikkiK1234 thanks for your post here in the Community although we're sorry to hear of the concerns you've raised here.

I'd like to look into this further for you and get this sorted. Kindly expect a PM from me to arrive shortly so I can look into this further for you, reply directly when you can!
Many thanks