The school offers specialist provision for children and young people with complex needs and disabilities, and in recent years staff have provided two additional weeks of extended school support in the summer.
However, the council is now reducing the funding for this service to save over £60,000 – leaving provision for only 25 children.
Selina Yau, who launched the petition, said: “We have recently been told that the council has cut funding for the two extra weeks of extended summer school, and will now only provide this service for 25 pupils instead of every pupil.
"This was not consulted with the parents and when we completed a questionnaire, the majority of respondents wanted the current model to continue, which is for every pupil to be offered a place.
"The majority of the pupils have not been offered a space, which will significantly impact on their mental health and wellbeing, as well as parents and carers.
"These two extra weeks allows pupils to socialise in a safe and supported environment by staff who know their care needs well.
"This time is also invaluable to parents and carers who are able to get a small break in care before the long summer holiday. These two weeks may not sound much, however, many parents viewed as a "lifeline" as they are able to use this time to focus on their other children's needs, being able to work before having to take full five weeks of annual leave due to unable to find care providers, or just focusing on their own health needs.
As parents and carers, we are appalled that the council made this decision without consulting with the children or us, and only giving us a very short period of notice.
"There are not many providers within the council who will take young people with such varied and complex needs, leaving parents unable to find alternatives.
"Although we have been told that there will be the new Clarkston After School Club, however, this will not be available until after the summer. Now, many pupils and family will suffer as a result.”
The council says the new model will support children with the most complex needs and will look to identify alternatives for other families.
A spokesperson said: “We understand that the proposed change to the structure of holiday provision at Isobel Mair will be difficult for those impacted.
"Unfortunately, like all councils, we continue to face extremely challenging financial pressures and when the budget for 2022/23 was set in March a range of tough savings had to be made.
"The additional holiday provision previously available for all in Isobel Mair has been redesigned to support children with the most complex needs, as we try to mitigate the impact of the saving as much as possible.
"In addition, we continue to work closely with a range of partners to explore and identify suitable alternative support measures which can be put in place for families.”
To sign the petition visit www.change.org/p/impact-of-significantly-reducing-isobel-mair-school-s-extended-summer-support-funding