Hello!
I wanted to add some comments to this thread to try and answer some of your questions and hopefully clarify a few things. We are learning a lot about merchant data as we go, so your patience is really appreciated. 
Grocery store vs petrol station
When we receive information about merchants there is a flag which tells us what kind of merchant this is. For example, it might say ‘Restaurant’, ‘Service station’, or ‘Grocery store’. This helps us categorise your transactions.
However, with regards to Tesco’s and Sainsbury’s, some people may go into the service station to buy their milk on a regular basis. Some service stations have quite a large food selection, so people may use the shop regularly for things other than petrol. We have no way of distinguishing between the two. We therefore made the decision to categorising all of the Tesco’s merchants as one.
We had a slight issue earlier this week where the stores were miss-categorised as transport, but this has now been fixed.
Categorising things
If you find that your petrol purchases are being categorised as groceries, you can very easily change the category to transport. In addition, if you want to add expenditure to sub-categories, for example splitting out fuel and airline travel, you can add notes. Notes are searchable.
Hopefully that helps to clear things up! 


Natasha