Would I have a good, (if any) argument?

Many of us were persuaded to have smart meters for our gas and electricity so that we could keep an eye on consumption and costs, something I was quite happy to do. Amongst the information available from the inhouse display unit (on my display unit at least) is the consumption figures, the cost per day / week / month and year together with the unit costs of electric, gas and the daily standing charges. 

Earlier in the year the unit prices went down because of government intervention but then reverted back to the original unit costs on 1st July. These unit prices changed on the display unit. However, and this is the crux of this query, whilst the unit price for gas was shown to revert on 1st July, the unit cost for electricity shown on the display unit has remained at the 'discounted' level. Looking online at my account details it shows that the unit price for electricity did revert to its original level on 1st July.

Now, what this means is that if I look at, and rely on, the figures displayed I will not be presented with anything like an accurate assessment of my costs for electricity. Would this error by my supplier be good enough grounds for an appeal come the anniversary bill for my account which I am assuming will be calculated at the higher level? This discrepancy could / will run into several hundreds of pounds. Thankfully, I have kept a weekly record of consumptions and do my own cost calculations,  (a simple self calculating Excel spreadsheet), so it won't come as a complete surprise.

In view of my experience, it might be worth others checking that the displayed unit costs are, in fact, the same as their account details show. Some of you may be in for a nasty surprise.