How to understand the confusing display of data usage on web site

[airwave]

Trying to see my data usage over the last few months using the web page https://myaccount.ee.co.uk/app/usage-since-latest-bill is very confusing.

eg

1) There are entries such as "24.98 GB used of null null". What does the null null mean?

2) Other entries say things such as "110.7 GB used of 120 GB", but I am on unlimited data so where is the "of 120Gb" coming from?

2) It is impossible to sort the entries into a meaningful order as the website programmer has made the elementary mistake of sorting dates alphabetically instead of chronologically. 

So if, for example, I sort ascending by 'Expires On' date I get 19 April, 19 Jul, 19 Jun, 19 May instead of 19 Apr, 19 May, 19 Jun, 19 Jul, This applies to all the sortable columns. 

3) Every time I try to see my itemised usage I get "An unexpected error occurred. Please try again later."

Any ideas how to get meaningful data from this page?

(screen shot below )

[airwave]

@EssexBoyEE 

Thanks for the information. That at least explains what is being shown.

I've been lecturing in database theory and SQL most of my career and still design databases. None of my students would dare to sort dates alphabetically (not after term 1 in the first year anyway!). It's such an elementary mistake to forget to sort by Julian date or similar or to store dates as yyyy-mm-dd  in the first place to make sure that May comes before June in ascending order and not the other way round. EE should be embarrassed having this mistake in such a public place.