SOP/LOR

Regarding LOR

Please help me here, I worked in Capgemini for 1 year 3 months until now and finding very difficult to get a LOR from my Manager as she refuses saying that I am not Authorized person to give LOR, please connect with HR. Then, I mailed HR they too responded that we don’t provide those kind of recommendation. Please suggest an alternative that from whom should I take the third LOR (I got the other two LOR from my professors) PS : I have a relative working in same company, can I take from him??