DSL Relocation - Connection Speed reduced?

Hello O2,

I applied for a DSL Relocation earlier this month, my current package is "o2 DSL L" with a speed of upto 50 Mbps. But this morning, I received a transfer contract letter from o2, it says my new DSL package is  "o2 DSL M" and the max speed limit will be 16 Mbps. How can I get this corrected? I would like to continue with my current speed of 50 mbps. 

I checked my new apartment address here -> VDSL & DSL Verfügbarkeit bei O₂ testen - DSL & Festnetz 

the check tells me that "o2 DSL L" with upto 100 Mbps is supported in the new address.