Got the job offer....buy the salary is less than discussed and advertised

So I got a job offer through today but the wage is quite a bit lower than advertised or discussed.

The job is advertised at 35k which was also mentioned in the interview.

The offer came through at 28k starting rising to 32k after probation!! I was a bit taken a back because I've calculated fuel costs and bills based closer to 35k.

I want to negotiate but I also don't want to come across as difficult. My skills and qualifications don't quite align with the job post but Im definitely not new to the tech I'll be using. Also there was no mention of starting at a lower wage anywhere in the job advert.

Any advice??