You need the TV Faults option when dialling 150 - if they go through a series of tersts then call back on the same option 10 minutes later and you should be able to talk to them to order a remote. It's best to call first thing on a morning, 8am, when it's not so busy
You could try the text messaging service.
Just send a text with a description of new remote to 07533 051809. Your message will go into a queue and a representative will respond to you as soon as possible. It may take a few days.
For now you could download the TV Control app and use that until you receive a replacement remote