Sagemaker Canvas: Pricing model has changed without warning

I have used Sagemaker Canvas for a while to teach students at a university.

Since last year (November) I have always been cautions about the usage, due to the high costs of the service.

Make sure to log out from Canvas to avoid per-hour charges and lower the training time as low as possible to not infer in compute costs.

A couple of weeks ago, when I did the same thing I got a bill of almost 300 USD of training costs.

I figured out that pricing was changed from computer hourly cost to cell-based cost (row x columns), no matter how much time was spent on the training job.

How can I get the pricing policy updates to prevent situations like that?

Here a proof that price was different last year:

https://medium.com/codenlp/be-aware-of-the-aws-sagemaker-cost-traps-a7a4f444de42

...The current price for Canvas is $1.9/hour. To train custom models, it will cost from $2.03 to $4.89 per hour of training time...