Ambulance workers in Aylesbury Vale who are members of the Unite union will still go on strike next week.
Meanwhile, strikes by the GMB and Unison have been called off following discussions with the government.
Unite's refused - accusing ministers of 'unreasonable' conditions.
South Central Ambulance Service said the strike on Monday will impact services.
Mark Ainsworth, Director of Operations at SCAS, said: “The escalation of the industrial action in SCAS now means it is at a level that has already been experienced by other NHS ambulance trusts during this dispute. We have been liaising closely with colleagues in those trusts to help ensure that SCAS as an organisation is as prepared as possible to continue prioritising our services to patients with immediately life-threatening or time critical conditions when industrial action is taking place.
“We have seen on previous days where significant industrial action in the NHS outside of SCAS has taken place, that the public have heeded our pleas to only call 999, or go to A&E, for immediately life-threatening or serious emergencies. I would urge people in our region to help us – and more importantly help those people who really need us in a life or death situation – to please keep doing this on 6, 8 and 20 March.
“We need people to seek help and advice from alternatives to 999, such as their own GP or local pharmacy where services are unaffected. For urgent help for people aged five or over, use NHS 111 online at 111.nhs.uk. Outside of normal GP hours, call 111 for children under five and only call 999 if it’s a life-threatening emergency.”