In the first instance, it would be better to deal with your concern by contacting SENCo, who may not realise that there has been an issue and may be able to rectify the situation or explain the school policies more clearly. If this is not successful and you still wish to complain, then you may wish to contact the Headteacher.

You are able to access some independent guidance and/or support by contacting Bury Special Educational Needs, Disability Information, Advice and Support Service (SENDIASS). This is a service organised through the Barnardos charity.
Their contact details are: Blue Pit Mill, Queensway, Castleton, Rochdale, Lancashire, OL11 2YW.
Phone 01706769634