Restricted for a low amount

My phone service has been restricted for a non payment of £18.03 + £3.87, I normally pay on time or early, I always pay more than my bill comes too so I end up in credit. I'm due to pay £25 on 20th August, my account is currently 2 days behind. Would it be possible to have my services re-instated as I need to use my phone for emergencies since I am disabled and need to use the phone to book appointments and keep in touch with family should I fall.