MR review, Wait times for decision

We informed the DWP that we wanted a mandatory reconsideration after they withdraw PIP from full to nothing following the annual review. Its was asked for within the 4 weeks required. We got a text message to say we had asked for the MR and one day later to say they had received the request in writing ( sent special delivery) . We have not received any written confirmation just the 2 text messages which im concerned about.
The response time for the review decision is up to 6 weeks. Its now been 7 weeks, is this 6 weeks period 'working days' as its been through the Christmas and new year holidays which would explain the delay? OR is the 4-6 weeks wait a 'Block of days' ie all days including Christmas day ect ect. I wouldn't expect them to be open on these days but do they still include them in their waiting time?

Question is now...DO we wait till next week or should we be concearned about having no contact other than the 2 text messages which were screen shot from the phone and saved to file.
Reading some accounts of how some 'requests' dissapear into the void is most worrying as the 4 week period to resond has long since expired.

Thankyou for your reassuring reply, from the first leg of the AR it took 3 months for a decision due to the backlogs I can only imagine due to the backlogs that a similar time frame for the MR decision is inevitable if not longer which is unfair or maybe a ploy for claimants to withdraw their MR application.
We have the text messages on file so maybe we will give it 8 weeks then if we get no notification then a quick call is on the cards to establish as to what is happening.