The word people are looking for is 'perishable'. If it's produced and not used, it is wasted. This is the single biggest problem with power generation, hence the desire for a national battery grid using Electric Vehicles. There are various methods for temporary storage of power using giant batteries, flywheels, hydro-electrics and heat-banks, but all those methods are very inefficient. Power is wasted through the act of storage, while in storage and when finally released.
This is not so much Microsoft's fault, nor was the power actually wasted - it would have been produced and paid for regardless due to contract; how it's used after is up to the customer. However, I still think near 300% surcharge to be extreme for this, it really should be just a flat contract rate for X units per month + excess over-usage. Producing something that a customer requested, it being paid for, not being used and then charging for the lack of use despite it being paid for is asinine. I blame the contract for this, rather than either company - but then I can blame both companies for agreeing to such a silly contract in the first place.