TL;DR: Got a job offer from higher-ups, HR invited for a call and never responded, even to the reminders.
For the past four years, I have been working remotly part-time as an independent contractor for the company while simultaneously finishing my degree. In December, I quit the company with the goal to complete the studies faster. The company supported the decision, with hope to have me employed on a full-time basis. I finalized the requirements for the degree and got certification 20 days ago.
Throughout this time I was in touch with the manager and did some minor support/dev work them. About a 1.5 month ago, the local director offered me a better position at the company. I accepted the offer and got mail from HR director (who started in December) asking to schedule a phone call to go over the details. Because we are situated in different time zones (and everyone's busy schedules), it is expected to setup/confirm date via email first, sometimes weeks in advance. I replied on the same day, sent reminders (after five and nine days), but haven't heard from HR ever since.
In parallel to this, the manager I was in contact with quit, cutting the "informal" source of information. I don't want to undermine HR and contact the local director right away, but I don't want to be at their mercy either. Having said that, the situation gives me very little promise in the work culture and makes me feel that I should reconsider the offer.
I am unsure how to react, on the one hand, I verbally confirmed the offer, and on another hand, the negligence of HR department worries me about the stability of the company as indicative by manager leave.