Faulty Oven?

[rachaelxx182]

Hi all, regarding the neil brothers 70L oven, I have had this for a few weeks now and last night it became erratic. It was set to 170 and the mugs were in. Part way through the cook it it shot up to 178 then dropped to 155 within the space of 2 minutes with the door closed and this was after it had already heated back up to 170 once the mugs had been put in. It did not get back up past 160 for the rest of the cook time which was usually 20 mins in total. I have tried it again today and took 50 mins to get to 160 with no mugs in. Then once the mugs were in again it took a further 26 mins to get to 170. I have contacted the neil brothers and they said they need to get advice from their chinese supplier. Has anyone had any experience with this type of issue and I am looking at a faulty oven? I have used the neil brothers a lot but never had to return anything and wonder how difficult this may be .