The basic problem is a lack of search or pattern-matching ability. The greater problem is the number selector only shows 40 numbers at a time, there is no way to scroll back/forward through the options, and no list.
This makes it extremely difficult to compare a selection of candidate numbers before deciding on which to purchase.
Even a simple list in numerical order would be better.
The only way to 'scroll' the 40-number limitation is to view another area then return to the existing area, at which point the 'next' 40 numbers are shown.
Except sometimes these aren't in numerical order! I've noted a few occasions where the 4th or 5th row show numbers that are totally out of sequence with the those around them, so one cannot even be sure of (eventually) cycling to the range of numbers you're considering!
When there a LOT of options this method of navigation is, quite frankly, user hostile.
I've failed to spend £500 with them last night simply because the hostile UX made me give up.