Comcast xfinity internet tries to double monthly bill , Internet

So I signed up with Comcast xfinity, "Performance - Special Offer", "Online Exclusive $29.99/month" for the first six months. Two months into this contract, I get a letter:

[begin quote]
Dear Valued Comcast Customer [sic - no name]

A recent review of our records indicates that you currently subscribe to a High-Speed Internet package and have been being [sic] billed incorrectly for this service at $29.99 per month which is the discounted rate applied when a customer subscribes to an additional Comcast service. The High Speed Only service rate for the Performance level of service is $62.95 per month. Effective with your December billing statement, your rate will reflect the High Speed Only rate.

If you have any questions regarding this letter or believe that you have received this letter in error, please contact us at 1-800-COMCAST. We value you as a customer and apologize for any inconvenience.

Sincerely,

Comcast Customer Care
[end quote]

So they know of course that they are wrong and thus include the second paragraph (The 29.99$ offer is still online and is of course correct). Wow, there's similar cases against Comcast on this site, so there's apparently a system behind this. Amazing.