A South Western Railway spokesperson said:
"We are extremely disappointed that the RMT union has once again called for their members to take disruptive industrial action. The deliberate targeting of services up to, and during, the Christmas period is typical of the lack of concern the RMT continue to have for our customers.
"The RMT has always said it wanted us to keep the guard on every train. That is what we have offered as part of a framework agreement if the RMT work with us to agree a method of operation for our new trains which fully utilises the new technology to improve safety, security and accessibility as well as day-to-day performance. Instead the RMT appear purely focussed on keeping control of train doors in a misguided attempt to hold power over the industry.
"Whilst we have shown commitment to the role of the guard by introducing over 80 additional guard roles since the start of our franchise, the RMT do not have the long-term interests of either our customers or our colleagues, including their members, at the heart of their actions.
"We remain committed to finding a solution that will help us build a better railway for everyone. We will do everything we can to keep customers moving during strike action."