Dr Wollaston, who represents the Totnes constituency, told a Westminster Hall debate her concern had been triggered by a number of incidents.
"People have contacted me either directly or indirectly to raise concerns about long waiting times faced by my constituents," she told MPs on Wednesday (12 July).
"One elderly lady was left for two hours at the roadside, on a baking hot day, waiting for a paramedic crew to arrive. She had serious neck injuries and was in some distress.
"Were it not for the kindness of passing strangers, things might have been even worse, but a consultant anaesthetist happened to be passing and was able to provide critical assistance."
Demand for ambulance services was rising at an extraordinary rate, said Dr Wollaston.
There had been a considerable rise in demand over the area of the South Western Ambulance Service NHS Foundation Trust during the five years to 2016-17.
Dr Wollaston said there had been a 19.2% increase in the Totnes constituency alone, a 29% increase in Plymouth and a 23.7% increase in Torbay.
"The challenge is far greater in a rural setting, for obvious reasons," she added and the SWASFT area is the most rural area in England.
"If we look at the activity for Devon, we see that 23.5% of SWASFT's activity is in that county, but that is matched by only 22.2% of its funding."
Dr Wollaston said there were "no concessions for rurality" when it came to government funding for ambulance services, despite the extra demands faced by SWASFT.
Calling on the government to acknowledge the impact of rurality on response times, she said SWASFT funding had fallen by by 2.46% per incident in 2017-18, compared with 2014-15.
"It has to meet the huge increase in demand with shrinking resource, in what is one of the most challenged areas in England because of rurality."
Although SWASFT was doing a good job in responding to 75% of emergencies within eight minutes, performance was lower in more remote rural areas.
When considering a county such as Devon, the government should look at the impact in the most rural parts of the constituencies – not just at the overall, top-line figure.
Responding on behalf of the government, health minister Philip Dunne said SWASFT was one of the highest-performing trusts in England.
An ongoing review was examining the way in which ambulance services responded to calls through the ambulance response programme.
SWASFT had been involved in piloting new operating models, said Mr Dunne.
The review had looked at a number of key issues for the south-west, including the provision of ambulance services in rural areas and putting an end to unacceptably long waits.
"A revised operating model is crucial to achieving sustainability in the ambulance service, given the growing demand," said Mr Dunne.
Trials had been independently evaluated, and the government hoped shortly to report findings and recommendations from NHS England.
A transcript of the full debate can be seen here.
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