A customer who may be in a rented property, for example, and who may need to move out on month 9 of the 12 month contract looks like facing a disconnection charge of £45 and paying up the remaining term at up to £55 a month.
That is correct - although they would also have had the first 6 months half price. In any case, Aquiss are probably not the best choice for someone who expects to move within the 12 month contract period.
This is something Aquiss need to look at.
I don't see why. There's a marketplace to choose from, and not all offerings suit all customers. There are other ISPs who offer even 1-month terms, if that suits you better.
Openreach charges for disconnection and for new activations, and Aquiss is essentially passing these charges on. If you were with BT or EE (say) then they would let you take service in the new property but would require you to sign a new 24-month contract, so the cost is amortised over the 24 months.
If you move regularly, let's say every 3-6 months, then they are probably making a loss on you; it's their choice whether to accept such loss-making customers.