Confusing dashboard info

I like the user friendliness of Bulb but increasingly find the dashboard information confusing and at odds. I currently have a credit balance of £266.43 and pay £90 p/m (reduced from £100 last month). My total energy usage in the last 5 months has been £274 (av. £54 p/m) as evidenced on my statement and this month they are offering me a refund of £157. Then, out of the blue, I get a statement saying my average usage is £109.03 p/m and suggesting I increase my DD to £109 p/m. Totally at odds. Any others have the same experience? I have ignored the request to increase as currently I have 5m cover in hand for present usage BUT have also not claimed the refund as I want to build a reserve for the higher winter usage, Any others had the same feeling that the dashboard is at odds to the actual statement usage?