BT special offer discount and CPI

According to https://www.bt.com/tell-me-more/?s_cid=con_email_GI_... I’m on the border of either 5.4% or 9.3% because my bill in Sep 2020 shows a prorated charge from 1 Sep 2020. My contract ends 31 Aug 2022.

The BT CPI increase email in Feb 2022 said my increase was £1.52

My last bill in Mar 2022 before the price increase shows:

Package Price £36.15
Special offer discount -£8.00
LRS discount -£19.99
Total £8.16

Looking at the figures, I can obtain a £1.52 increase by taking the package £36.15 subtracting the £8.00 special offer discount and applying 5.4%. So due to timing in 2020, I was given the lower rate.

Package Price £36.15
Special offer discount -£8.00
Total before CPI £28.15
5.4% increase £1.52

Bills after the above show the base price increasing by £1.52 with the LRS and discount remaining the same.

To me, it looks like BT take into account the “special offer discount” (due to having a contract with them?) into account when calculating the monetary value of the CPI increase.

Have others seem similar? It would be good if there was an example on BT's website.

I’m trying to guestimate potential CPI increases and the monthly / total contract payment over the next 24 months using an increase of 18% for Mar 2023 and Mar 2024 using the current offer from BT. Every little helps!

AFAIK all providers seem to have CPI + % apart from possibly Now and some 1 month providers like Pulse8.

BT are not the cheapest but in my 30 years experience, I haven't had any hassle.

I've been called by BT Newcastle regarding my migration to another provider. I'm staying with BT. The lady agreed with my comments in my first post. I do note that she was in retention and not billing but I think my past experience with a CPI increase is correct.

Thank you for all that have viewed the post.