Apprenticeship Advice

I've been in my business admin apprenticeship since July and i'm still learning about different things aka reverse cameras and parking sensors for vehicles etc.

So on tuesday one of the installers went out to the job and it was wrong the customer wanted a dual reverse camera not a single. However, when i've gone and looked through every bit of conversation notes theres no mention of them saying they wanted a dual camera.

It's a small company so the office is made up of myself, my manager and the MD, with 4 installers. My manager was off due to being ill so it was just me and the MD in the office that day. I mentioned it to the MD when the installer called. After speaking to the installer he called me into his office. Said it was embarrassing to the customer that I made this mistake. The customer was lovely about it and hasn't complained and was still willing to pay for the work done on the day. We've ordered a new camera and managed to book him back with the new kit (booked for 6 days later as it takes a few days for the kit to come in.

However, the MD yesterday would not let me answer any sale enquiry emails or phones call. So I asked if I could do my coursework instead as on Thursday that's a day that gets set aside for any coursework I need to do. He said I wasn't allowed as there was only me and himself in (my manager was feeling better but working from home and she had all my normal tasks on top of her own) and instead I just cleaned as he asked me to hoover etc. Then today my manager was back in the office but she still had all my tasks and i'm not allowed to do anything. Going forward starting from yesterday any job sheets I make have to be signed by someone.

Now I'm worried i'm going to be sacked for a mistake when i'm still learning. Even more so by the fact i'm not allowed to do anything and feel like i'm being punished.

Can anyone suggest what might happen and what I could do.