Chain problems, new bike from Wiggle

[Pebbleheed]

I replaced my old mountain bike with a new Cube Attention 29 from Wiggle yesterday. It came boxed up and partially assembled. I had to fix the handlebars and peddles to it.

I took it for a test ride last night and noticed a few issues.

1) the chain is noisy. Clicking in several gears. The change isn’t that smooth either.

2) some of the gears jump when I’m riding. Even on flats, not under load up hills.

3) the disk breaks seem soft with little stopping power and are nothing like my old bike’s disks.

I’m not the most technical minded with bikes and my local bike shop is shut so I can’t get advice or help.

Should this be easy to fix or do I need to contact wiggle? They were meant to have set the bike up for me prior to sending it out with me just having to install the two bits above. But it doesn’t feel set up right now.