UK - twins at 12 week scan what happens next...

I wondered if anyone could give any advice? They found at my 12 week scan that I’m having identical twins that share a placenta and possibly a sac, they said the consultant will be in touch. 2 weeks later still nothing, and no additional information on twins or what happens next, I know having multiples is high risk so thought they would have been in touch by now. Does anyone know the routine? Or what I can expect to happen now? I’ve phoned the hospital many time and they tell me to wait for the letter. (UK by the way)

Thanks x