Do you mean a Thetford toilet? if so www.thetford-europe.com look up your toilet or contact Thetford my guess need a plunger repair kit.or contact them via on line form
Telford toilet! you'd never get one in a caravan or motor home they are portable site toilets site as in building site for the workforce. Or a public event.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix caravans/motorhomes.